The Tesla Semi Weighs In – Part 3

Tesla Semi


Tesla Semi

Tesla Semi

Like wrestling and boxing, you can’t play the commercial trucking game if you don’t “make weight” for your class. The Tesla semi wants to join the Class 8, 80,000 lb division. To compete, Class 8 semi-tractors have to “make weight” while hauling a 15,000 lb trailer and 45,000 lb freight payload. Most of the current-generation aero line-haul diesel tractors weigh-in at 19,000 lb and carry 700-1,400 miles worth of fuel onboard. To be competitive, Tesla has to weigh-in at no more than 20,000 lb while carrying (from George’s battery pack article) a 9,500 lb, 500-mile-range battery pack.

*This is the third of four articles on Tesla’s semi truck. Links to other related articles below:

Part 1

Part 2

Tesla Semi

Tesla Semi Slide 1

To “make weight” with that pack, Tesla took the conventional semi-tractor concept and put it on the “Tesla Semi Diet.”

Tesla Semi

Tesla Semi Slide 2

Tesla Semi

Tesla Semi Slide 3

Fortunately, “lightweighting” is a growing trucking-industry trend and various off-the-shelf techniques are now available. Lighter tractors mean either more billable payload capacity or lower operating costs.’s lightweighting white paper describes these techniques and approximate weight savings. Based on what we’ve seen from the Tesla reveal and walk-around videos, we know or can make educated assumptions about what Tesla has done to “make weight.”

Tesla Semi

Tesla Semi Slide 4

Tesla revealed their Semi as a day-cab without a sleeper. Walk-around videos confirmed super-single driver wheels/tires on the white line-haul version and individual Model-3-style drive motors for each driver wheel. The suspension appears to be a conventional semi air-suspension.

We noted the Tesla Semi uses many of the same aero-features now used on state-of-the-art Class 8 diesel tractors such as the Kenworth T680 illustrated on the “Tesla Semi Diet” illustration, Air dams, Chassis fairings, Trailer gap-reducing side extenders, and Driver wheel covers or disc hubcaps.

Tesla Semi

Slide 5

Diesel engines, fuel, transmissions, and accessories all add up to a lot of removed weight when converting to an electric drive. Note also that the all-electric Tesla Semi also eliminates the “DEF” tank and fluid. Most current-generation diesel engines must inject a water-urea solution called “Diesel Exhaust Fluid” (DEF) in the exhaust to reduce EPA NOx emissions. The urea functions similarly to an automotive catalytic converter in converting the NOx to water and nitrogen.

And, the most rewarding weight component to remove? The 200 gallons of diesel that must be re-purchased over and over and over as it is poured into the engine and converted to CO2, NOx, and particulates throughout a diesel tractor’s life.

Tesla Semi

Slide 6

But, what comes out must go back in. Though electric motors, gearboxes, and accessories are much lighter than their diesel equivalents, the portly 9,500 lb battery in the belly negates about all of the weight savings.

Tesla Semi

Slide 7

Tesla Semi

Slide 8

Adding a new electric propulsion system to the stripped-down Class 8 “glider”, we estimate the 500-mile range Tesla semi comes in right around 20,000 lb – the upper limit to guarantee capacity to haul a “regular” payload and trailer without exceeding the Federal 80,000 lb Class 8 weight limit. The 300-mile range version, with a smaller 510-kWh (estimated) battery pack, weighs in at a slim 16,000 pounds. Almost light enough for welterweight.

Tesla Semi

Slide 9

*George Bower contributed to this article.

Categories: Tesla


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35 Comments on "The Tesla Semi Weighs In – Part 3"

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I am amused that the outgoing fuel weight is comparable to the incoming reusable energy storage device weight: 14%.

200 gallon of fuel is good for about 1400 miles not the 500 of the 9500 lb battery.

Com’on Dan It’s their first round of trucks … plus i believe 500 miles a day is your max . I know you shouldn’t be able to drive 1400 a day in a rig legally

Great series of articles!

I seen on Bloomberg where buses will be 50% if the global fleet by 2025. I think it’s great but I’d be surprised if it can get there that soon.
With trucks and semi trucks starting to enter the mix transportation will be clean sooner than rather than later.

Good article.

Yes, great, informative article!!!

@ Keith and George:

Thank you again very much!

…for all the hard work and the in-depth research you’ve put in on this series of articles. I appreciate it greatly!

You put Navigant and similar “market research” companies to shame. This is how they should be doing their jobs! It’s doubly shameful when you consider that those guys are getting paid for their shoddy work, whereas you — I presume — are not; or if you are, it’s likely only a token payment.

You’ve definitely set the bar pretty high here. Again, well done! 🙂

Last one on cost is up today around 1 PM Fri. It could be a bit controversial!Check back

Geo and K

Thanks so much for the feedback, Pushmi. George and I working together illustrate a classic Pushmi-Pullyu truth: two heads are better than one:)

one and a half would be a better description:)

Great article guys. I’d quibble as to whether a the 19,000 lb for a sleeper cab includes 200 gallons of diesel. Also, did you include motor and power electronics cooling? That won’t be as heavy as a diesel engine but will still have to shed a lot of heat on a long mountain climb.

Finally, is there any double-counting. For example, counting diesel engine elimination but also counting diesel engine weight reduction in the “lightweighting” portion?

@ Doggydog

see slide 4. No credit for lightweighting the diesel engine was taken until it was removed. So no double booking.

@ doggydogworld:

Always appreciate your comments. As George noted, I don’t think we double-counted. But be sure to double-check our math in the cost-analysis post due up in a few yours. It was pretty complicated and we might have slipped somewhere.

Funny story with your handle:

Back in the 90’s, our family hosted a foreign exchange student from Indonesia for a year. It was early in her year and she was still mastering American English. She heard a phrase at school that confused her. She said her teacher said something about “it being a doggy-dog-world”. We LOL’ed and told her about cannibalistic-canine American slang!

Every post of yours reminds me of her.

The fuel in a Diesel engine is NOT converted to NOx… When complaining about false statements in the mainstream media, please stay accurate yourself…

Combined with air, it is indeed converted to CO2 (overwhelmingly), NOx (in small amounts that cause huge problems for human health) and particulates.

What did you think it was converted to?

The fuel is converted into CO2 and H2O. Actually more water than CO2. NOx is a byproduct formed from atmospheric nitrogen and oxygen because of the very high temperature of the diesel combustion.


What is the “mainstream media”?

Everything that isn’t Fox.

Doncha just love that persecution complex they have?

I was referring to Ev enthusiasts often accusing the mainstream media about misrepresenting the benefits of EVs and similar, which might be accurate. In either way one should avoid consequently making false statements as well, even if there are little.

Amazing how an “impossible thing” comes to life.
Like launching and landing and launching a rocket.
Ignore the naysayers.
Improved battery technology will only make it better.

Addition of a Capstone Turbine Microturbine generator as a range extender could replace a lot of batteries and battery weight. 65kW generator isn’t much larger than a 2-liter Coke bottle, doesn’t require lubrication and burns diesel or natural gas clean. The Nicola One project was going to use Capstone Turbines but went with hydrogen fuel cell design instead. This would be a good long range class-8 truck.

I think the time for this type of solution has pretty much passed, if it were already fully developed and on the market today maybe it would make sense. But by the time you could get a program like this finished and into the market I think any drawback for a full EV solution will have been mitigated.

If only the trucking world had been required to advance their fuel economy since the 70s like every other mode of transport.

Microturbines arew a a bit exotic, but CNG ICE is slowly making inroads. More truck stops have installed CNG stations. Diesel prices are going up again.

When you can buy NG for the equivalent of $2/gallon and have no injector issues, longer oil changes, no DEF, and other maintenance headaches go away, it can make sense.

I’m curious why CNG doesn’t require DEF. Does CNG in a compression ignition engine burn cooler than diesel does? Is the NO2 decreased due to some other reason?

Not sure how many models use them yet, but there are also many ‘simultaneous dual fuel’ Diesels out there. Under full loading they use about 10% oil and 90% Natural Gas. Under very light loading its almost all oil.

As far as efficiency goes, Natural Gas is right up there since its Octane Rating is 130.

The efficiency of open-cycle turbines is rather unimpressive compared to modern reciprocating engines. Not sure about “clean” — but either way, I’m not sure why you would even bring it up in a discussion of zero-emission trucks…

(As far as range extenders go, I wonder whether a combined cycle turbine would be doable. It would be more efficient, and would avoid the problem of extremely hot exhaust gas… Plus, I’m amused by the idea of filling up the water tank, like a “good” old steam engine 😉 )

Great article, I look forward to Part 4.

Appreciate all the work that went into this article.

Anyone knows how much the scania, Volvo or man trucks weigh in Europe?

I guess that leaves us with a target for battery weight loss

This could be used for short haul, but not long haul, for that you need fuel cells.

Omg! I had no idea! Great that you know! Why don’t you can tesla and all the companies that have ordered this truck already and tell them? All the engineers, scientists and elon musk! They have gotten this an wrong.